1. Technical Field
The present invention relates to a process control system that manages a plurality of semiconductor wafers as one lot, automatically issues instructions about process conditions to a fabrication facility (semiconductor fabrication apparatus) and further, collects measurement results, for example, from measuring instruments on-line. More particularly, the invention relates to a method and apparatus for process control of a semiconductor device fabrication line where input and correction of data for automatically setting levels (i.e., positions or priority levels) in a plurality of experimental steps are performed with ease.
2. Description of the Related Art
In a semiconductor device fabrication line, there has been adopted a process control system by which fabrication facilities are not specified for respective uses in fabrication of an xe2x80x9cexperimental devicexe2x80x9d (i.e., a prototype product) and in fabrication of a xe2x80x9cmass fabrication devicexe2x80x9d (i.e., a product) in a fixed manner, but, instead, a fabrication schedule for an experimental device is incorporated in a fabrication schedule for a mass fabrication device, and thus, the fabrication facilities in a single line are flexibly shared for uses in fabrication of experimental devices and in fabrication of mass fabrication devices in a compatible manner (see, for example, JP-A 10-11108).
FIG. 1 is an illustration showing a conventional process management system of this kind in which mass fabrication devices and experimental devices are mixed. That is, a lot-base management host computer 1 is a host computer that performs management of wafers for each lot and manages process conditions for each lot, progress management for each lot, the correspondence between a carrier ID and a lot ID, and the correspondence between a slot ID and a wafer ID in each lot. Further, respective semiconductor device fabrication apparatuses 2 perform various processing such as etching, ion implantation, oxide film formation and others on wafers in a lot to be processed according to conditions provided from the lot-base management host computer.
In the case of a special operational step including an experimental device, wafers in a carrier are divided, such that a lot and a process condition are related in a one to one correspondence. In this case, a carrier in process is loaded into a semiconductor fabrication apparatus 2. The semiconductor fabrication apparatus 2 inquires of the lot-base management host computer 1 about lot information using the loaded carrier ID as a key. The lot-base management host computer 1 transmits a process condition corresponding to the lot to the semiconductor fabrication apparatus 2. The semiconductor fabrication apparatus 2 performs processing of wafers according to the instructed process conditions, thereby completing operations over the entire lot.
On the other hand, in the case where an operation step is xe2x80x9cnormalxe2x80x9d, i.e., only associated with a mass fabrication device, a carrier in process is first loaded into a semiconductor fabrication apparatus 2. The semiconductor fabrication apparatus 2 inquires of the lot-base management host computer 1 about lot information using a loaded carrier ID as a key. The lot-base management host computer 1 transmits process conditions corresponding to the lot to the semiconductor fabrication apparatus 2. The semiconductor fabrication apparatus 2 performs processing of wafers according to the instructed process conditions, thereby completing operations over the entire lot.
Further, FIG. 2 is a flow chart showing a conventional process control system. First, in a case where experimental steps with a plurality of levels (i.e., positions or priority levels) are included in one carrier (step S1), carriers are divided into groups with respective levels while confirming information from the lot-base management host computer 1 at a wafer sorter (step S2). That is, the wafers are rearranged into the carriers according to levels at the sorter based on data acquired from the lot-base management host computer 1, wherein wafers are divided into the carriers with respective levels, related in a one carrier to one level correspondence (step S3). After such a rearrangement, carriers to be processed are loaded into the semiconductor fabrication apparatuses (step S4). Then, processing information is downloaded on the semiconductor fabrication apparatuses 2 from the lot-base management host computer 1 (step S5) and processing of wafers in the carriers are performed in the semiconductor fabrication apparatus (step S6). Such processing is performed on all the carriers into which wafers are rearranged according to levels (step S7). Thereafter, information from the lot-base management host computer 1 is confirmed at the wafer sorter, wafers in the carriers are integrated into the respective levels, and each group of the wafers thus integrated is placed in one carrier when the wafers have been processed in the same condition (step S8).
FIG. 3 shows a conventional xe2x80x9cmasterxe2x80x9d (i.e., a master table database or other file) for experimental levels. In the processing corresponding to the master illustrated, a set of steps a, b and c is repeated in sequential order a plurality of times in a serial manner. In a conventional system, a master of experimental levels for a wafer number and each step is prepared, the master of experimental levels is stored in the lot-base management host computer, and instructions are issued to semiconductor fabrication apparatuses based on the master for experimental levels.
However, in such a conventional technique, since a host computer has only performed management of wafers for each lot, the host computer has not been able to issue a complicated process condition as instructions. Further, when there is a plurality of process conditions within one lot, the conventional technique has problematically had poor efficiency in aspects of lost productivity, time and transportation, since one lot has to be divided into groups of wafers according to process conditions, such that one condition corresponds to one lot.
The conventional technique has had further problems:
As shown in FIG. 3, in a conventional system, since process conditions for each wafer and specification data for measurement are dispersed over respective steps, the relationship between steps cannot be integrally grasped for each wafer. Therefore, since set data for a plurality of steps constituting an experiment cannot be displayed for each wafer, there arises a necessity to enter level data into respective steps, which not only makes grasping an overview of an experiment hard, but also makes entering data burdensome. Besides, since a comprehensive level that plays an auxiliary role in viewing the overview cannot be automatically calculated, input errors may be generated.
An object of the invention is to provide a method and apparatus for process control of a semiconductor device fabrication line by means of which experimental levels in a plurality of steps can be viewed at a given time, a process condition can be displayed for each wafer, and setting and management of experimental level data are performed with ease.
A first process control method for a semiconductor device fabrication line according to the present invention is a method for managing fabrication in a semiconductor fabrication line, using a lot-base management host computer that performs management for each lot by managing a process condition for each lot, a correspondence between a carrier ID and a lot ID, and a correspondence between a slot ID and a wafer ID in each lot; a wafer-base management host computer that performs management for each wafer in a lot by managing a process condition corresponding to a wafer number in a lot; and a converted condition instructing section that transmits data acquired from the lot-base management host computer and the wafer-base management host computer to a semiconductor fabrication apparatus. Said method comprises the following steps. Namely, the semiconductor fabrication apparatus inquires of the converted condition instructing section about lot information based on a carrier ID loaded thereinto. The converted condition instructing section acquires a process condition for the lot, slot ID information and wafer ID information from the lot-base management host computer, and in a case where wafers in process are experimental wafers, not only acquires information of each wafer in the lot from the wafer-base management host computer, but transmits a process condition corresponding to the slot ID to the semiconductor fabrication apparatus.
A second process control method for a semiconductor device fabrication line according to the present invention comprises the following steps. Namely, when the semiconductor fabrication apparatus inquires of the converted condition instructing section about lot information based on a carrier ID loaded thereinto, then the converted condition instructing section acquires a process condition for the lot, slot ID information and wafer ID information from the lot-base management host computer, and then, the converted condition instructing section, in a case where wafers in process are experimental wafers, not only acquires information of each wafer in the lot from the wafer-base management host computer, but transmits a process condition corresponding to the slot ID to the semiconductor fabrication apparatus.
A process control apparatus for a semiconductor device fabrication line according to the present invention comprises a lot-base management host computer that performs management for each lot by managing a process condition for each lot, a correspondence between a carrier ID and a lot ID, and a correspondence between a slot ID and a wafer ID in each lot; a wafer-base management host computer that performs management for each wafer in a lot by managing a process condition corresponding to a wafer number in a lot; and a converted condition instructing section that transmits data acquired from the lot-base management host computer and the wafer-base host computer to a semiconductor fabrication apparatus. The wafer-base management host computer stores process conditions for respective levels and machine numbers of semiconductor fabrication apparatuses in use in the form of a matrix using experimental steps and wafer numbers as a master for experimental levels and issues a process condition to the semiconductor fabrication apparatus through the converted condition instructing section according to the master for experimental levels.
The process control apparatus for a semiconductor device fabrication line according to the present invention may have a sorter that reads the ID of a wafer inserted in a slot of a carrier and transmits a slot ID and the wafer ID to the lot-base management host computer, or a sorter that reads the ID of a wafer inserted in a slot of a carrier, transmits a result of the reading to the lot-base management host computer and, when a correspondence between the slot ID and the wafer ID does not coincide with a correspondence therebetween that is stored in the lot-base management host computer, transfers the wafer to a correct lot.
Further, the master for experimental levels can include a control characteristic specification for each wafer in addition to a process condition. Still further, the present invention can comprise a display unit for displaying the master for experimental levels; and a correcting unit for correcting the contents of the master in display. Yet further, the present invention can comprise a display unit for determining and displaying the number of comprehensive levels as results of assigning levels in a plurality of experimental steps.